Vehicles having a passive entry system require a means of determining when an operator of the vehicle has approached the vehicle and wants to begin the electronic authorization process. A sensor or switch mounted on or near the outside door handle may require the operator to touch or pull the handle to begin the authorization process. When the operator touches or pulls the handle, the sensor sends a signal to a control unit in the vehicle to begin the authorization process. If the operator is authorized to enter the vehicle, an unlock signal is sent to the latch and the door can be opened.
For the passive entry system to feel responsive, the steps of the authorization process must be accomplished quickly. Since the handle switch or sensor is the first step of the passive entry sequence, it is important for the switch or sensor to detect the presence of the operator as soon in the cycle as possible. Several methods can be used to achieve these results. One type of system uses a non-contact sensor to detect the near presence of an operator's hand before it contacts the door handle. This first type of system has a cycle time advantage, but comes at a cost premium. A second type of system uses a sensor to detect the presence of the operator when the operator touches the door handle. This second type of system begins to wake up the passive entry system before the operator begins to move the door handle. This second type of system has a slight time cycle advantage, but also comes at a cost premium. A third type of system uses a simple switch that detects the initial movement of the door handle once the operator begins to pull it. This third type of system must wait for actual movement of the door handle to begin the authorization process, but has a large cost advantage over the other two systems.
Each of the methods described above assumes that the sensor or switch is mounted on or near the outside door handle. Significant cost is added to the manufacturing of the vehicle when the sensor or switch is mounted on or near the outside door handle, because a separate wire harness and connector are required to provide power to and from the sensor or switch. Specially-equipped door handles are required and may require additional suppliers.